Luz is a teenage girl who is imaginative but not very social. One day, she comes upon a portal to a mysterious world called the Boiling Isles, where she encounters the witch Eda and the demon King, whom she has to join on a quest so that she can return home.
After Luz readies herself to be an apprentice witch, she's upset to end up delivering Eda's potions instead, whereupon she runs into the wizard Adegast, who leads her to believe she is the "chosen one" to recover a magic item.
As Luz grows frustrated with Eda's teaching method, she finds out about a school that teaches magic, much to her delight. There, she befriends a student called Willow, whom she tries to help; however, drastic consequences ensue.
As Eda strives to learn magic, King tries to teach her, but his attempt brings about an unfortunate chain of events, whereupon the two must join forces to subdue a mysterious monster.
During an annual event where new witches can find information about different covens before joining one, Luz and Eda discover the Emperor's Coven, whose leader is Lilith, Eda's sister, after which Luz challenges Amity to a witches' duel, which ends in an unexpected way.
After Luz invites Gus and Willow over to the Owl House without Eda's permission, they unintentionally give the house legs and bring it to life, causing chaos all over Bonesborough.
While at the library, Luz runs into Amity, who treats her coldly, and her twin siblings, Emira and Edric, who take to her. As Luz joins the twins on mischievous antics, things take an unexpected turn, causing Luz and Amity to make up.
As Luz, King, and Eda envy each other, thinking that the others have it easy, they decide to swap their bodies for a day, making a bet out of it; however, things don't go as planned for any of them.
After Gus invites the still banned Luz to Hexside School's Human Appreciation Society, Luz gets into trouble, whereupon the guilt-ridden Gus tries to help her. Meanwhile, Eda attempts to fulfill Luz's dream of attending magic school.
While out with her friends, Luz inadvertently loses Owlbert, and in order to get it back, she has to pass a series of tests given to her by the Bat Queen. Meanwhile, King tries to help Eda return to her normal self after she's turned into the owl beast again, yet the elixir proves ineffective.
While collaborating with Luz on a book, King disregards her ideas but eventually has to ask for her help when he gets into trouble. Eda learns that Lilith wants to find the Bloom of Eternal Youth for the Emperor, but as Lilith mocks Eda, the latter attempts to beat her to it.
In order to have the same classes as Amity at Hexside, Luz discovers that she needs to learn another spell, so Eda takes her to The Knee, a magical place covered in snow, to teach her. There, they run into Amity and her siblings, and the five of them end up having a thrilling adventure.
On her first day at Hexside, Luz gets into trouble and ends up in detention; meanwhile, a school inspector comes to visit the school but is later revealed to be a magic-draining Greater Basilisk, so Luz and the other students, who were detained for using mixed magic, team up to defeat him.
Eda, Luz, and King go to a carnival, where they bump into Gus and Willow. As Tibbles, the owner of a miniature circus, takes advantage of King's feeling left out, he talks him into shrinking Gus and Willow, over which Luz quarrels with King, leading to an unexpected turn of events.
During a class in which memories are turned into photos, Amity burns a photo of her and Willow when they were friends. However, the fire spreads and destroys Willow's other memories, whereupon Eda gets Amity and Luz inside Amity's mind to restore her memories, leading to surprising revelations.
Luz discovers that Prom at Hexide is called Grom and that it involves choosing a student to battle Grometheus, a demon that takes the shape of one's greatest fear. As Amity is chosen to be the Grom Queen, Luz volunteers to take her place. Eventually, they both join forces to take on the demon.
As Boscha, the grudgby team captain, bullies Willow, Luz tries to help her friend, challenging Boscha to a grudgby match on behalf of Willow. While training, Luz gets carried away, causing Willow and Gus to quit the team, whereupon Amity reveals to Luz a secret that makes her change her ways.
Luz goes on a field trip to the Emperor's castle as she finds out that the castle has a room containing magic relics, including an item that could cure Eda's curse. As Lilith finds Luz there and holds her captive, a confrontation occurs between Eda and Lilith that takes a drastic turn.
After Eda's capture, Lilith is horrified to learn that the Emperor plans to have Eda petrified. As Luz sets out to save Eda, she's faced with a tough decision that might cost her a lot.